Pneumatic tire

Abstract

A tread pattern of a pneumatic tire includes an inner circumferential main groove and an outer circumferential main groove that have groove walls extending in a tire circumferential direction while the angle of the groove walls relative to a contact surface varies with a predetermined amplitude, an inner lug groove extending from the inner circumferential main groove toward the outer circumferential main groove, an outer lug groove extending from the outer circumferential main groove toward the inner circumferential main groove, and a sipe configured to communicate the inner lug groove with the outer lug groove. A pair of chamfered surfaces are provided on walls of the sipe along an extension direction of the sipe on the contact surface.

The invention claimed is: 
     
       1. A pneumatic tire having a tread pattern and a predetermined mounting direction in a vehicle inner-outer side, the pneumatic tire comprising:
 an inner circumferential main groove having groove walls each extending in a tire circumferential direction while angles of the groove walls with respect to a contact surface vary with a predetermined amplitude; 
 an outer circumferential main groove located away from the inner circumferential main groove toward a vehicle inner side, the outer circumferential main groove having groove walls each extending in a tire circumferential direction while angles of the groove wall with respect to the contact surface vary with a predetermined amplitude; 
 an inner lug groove extending, from the inner circumferential main groove toward the outer circumferential main groove, partway along a region of the land portion between the inner circumferential main groove and the outer circumferential main groove; 
 an outer lug groove extending, from the outer circumferential main groove toward the inner circumferential main groove, partway along a region of a land portion between the inner circumferential main groove and the outer circumferential main groove; and 
 a sipe configured to communicate an end portion of an outer circumferential main groove side of the inner lug groove with an end portion of an inner circumferential main groove side of the outer lug groove; wherein a width of the sipe expands toward a tread surface due to a pair of chamfered surfaces provided on walls of the sipe along an extension direction of the sipe on the contact surface; 
 the inner lug groove extends from a location where an angle formed by a groove wall on the outer circumferential main groove side of the inner circumferential main groove and the contact surface is greater than an average value of a maximum value and a minimum value of the angle formed by the groove wall on the outer circumferential main groove side of the inner circumferential main groove and the contact surface; and 
 the outer lug groove extends from a location where the angle formed by a groove wall on the inner circumferential main groove side of the outer circumferential main groove and the contact surface is greater than an average value of a maximum value and a minimum value of the angle formed by the groove wall on an inner circumferential main groove side of the outer circumferential main groove and the contact surface. 
 
     
     
       2. The pneumatic tire according to either  claim 1 , wherein a center position in a width direction of the sipe coincides with a center position in a groove width direction of the inner lug groove and the outer lug groove, at a connection portion of the sipe with the inner lug groove and the outer lug groove. 
     
     
       3. The pneumatic tire according to  claim 1 , wherein:
 a length of the inner lug groove and a length of the outer lug groove are different from each other. 
 
     
     
       4. The pneumatic tire according to  claim 1 , wherein:
 the length of one of the inner lug groove is longer than the length of the outer lug groove. 
 
     
     
       5. The pneumatic tire according to  claim 4 , wherein:
 when the length of the outer lug groove is denoted as LA and the length of the inner lug groove is denoted as LB, then 1.8≤LA/LB≤2.2. 
 
     
     
       6. The pneumatic tire according to  claim 4 , wherein:
 when the length of the inner groove is denoted as LC and the length of the outer groove is denoted as LD, then 1.0≤LC/LD≤1.2. 
 
     
     
       7. The pneumatic tire according to  claim 1 , wherein an interval between a pair of ridge lines formed by the chamfered surfaces and the contact surface is equal to a groove width of the inner lug groove and a groove width of the outer lug groove. 
     
     
       8. The pneumatic tire according to either  claim 7 , wherein a center position in a width direction of the sipe coincides with a center position in a groove width direction of the inner lug groove and the outer lug groove, at a connection portion of the sipe with the inner lug groove and the outer lug groove. 
     
     
       9. A pneumatic tire having a tread pattern and a predetermined mounting direction in a vehicle inner-outer side, the pneumatic tire comprising:
 an inner circumferential main groove having groove walls each extending in a tire circumferential direction while angles of the groove walls with respect to a contact surface vary with a predetermined amplitude; 
 a first outer circumferential main groove located away from the inner circumferential main groove toward a vehicle inner side, the first outer circumferential main groove having groove walls each extending in a tire circumferential direction while angles of the groove walls with respect to the contact surface vary with a predetermined amplitude; 
 a first inner lug groove extending, from the inner circumferential main groove toward the first outer circumferential main groove, partway along a region of a land portion between the inner circumferential main groove and the first outer circumferential main groove; 
 a first outer lug groove extending, from the first outer circumferential main groove toward the inner circumferential main groove, partway along a region of the land portion between the inner circumferential main groove and the first outer circumferential main groove; 
 a first sipe configured to communicate an end portion of a first outer circumferential main groove side of the first inner lug groove with an end portion of an inner circumferential main groove side of the first outer lug groove; 
 a second outer circumferential main groove located away from the inner circumferential main groove toward a vehicle outer side, the second outer circumferential main groove having groove walls each extending in a tire circumferential direction while angles of the groove walls with respect to the contact surface vary with a predetermined amplitude; 
 a second inner lug groove extending, from the inner circumferential main groove toward the second outer circumferential main groove, partway along a region of the land portion between the inner circumferential main groove and the second outer circumferential main groove; 
 a second outer lug groove extending, from the second outer circumferential main groove toward the inner circumferential main groove, partway along a region of a land portion between the inner circumferential main groove and the second outer circumferential main groove; and 
 a second sipe configured to communicate an end portion of a second outer circumferential main groove side of the second inner lug groove with an end portion of an inner circumferential main groove side of the second outer lug groove; 
 wherein 
 a width of the first sipe expands toward a tread surface due to a pair of first chamfered surfaces provided on walls of the first sipe along an extension direction of the first sipe on the contact surface; 
 a width of the second sipe expands toward the tread surface due to a pair of second chamfered surfaces provided on walls of the second sipe along an extension direction of the second sipe on the contact surface; 
 the first inner lug groove extends from a location where an angle formed by a groove wall on the vehicle inner side of the inner circumferential main groove and the contact surface is greater than an average value of a maximum value and a minimum value of the angle formed by the groove wall on the vehicle inner side of the inner circumferential main groove and the contact surface; and 
 the first outer lug groove extends from a location where an angle formed by a groove wall on the vehicle outer side of the first outer circumferential main groove and the contact surface is greater than an average value of a maximum value and a minimum value of the angle formed by the groove wall on the vehicle outer side of the first outer circumferential main groove and the contact surface. 
 
     
     
       10. The pneumatic tire according to  claim 9 , wherein:
 when the length of the first outer lug groove is denoted as LA and the length of the first inner lug groove is denoted as LB, then 1.8≤LA/LB≤2.2. 
 
     
     
       11. The pneumatic tire according to  claim 9 , wherein:
 when the length of the second inner lug groove is denoted as LC and the length of the second outer lug groove is denoted as LD, then 1.0≤LC/LD≤1.2. 
 
     
     
       12. The pneumatic tire according to  claim 9 , wherein:
 an interval between a pair of ridge lines formed by the first chamfered surfaces and the contact surface is equal to a groove width of the first inner lug groove and a groove width of the first outer lug groove. 
 
     
     
       13. The pneumatic tire according to  claim 9 , wherein:
 an interval between a pair of ridge lines formed by the second chamfered surfaces and the contact surface is equal to a groove width of the second inner lug groove and a groove width of the second outer lug groove. 
 
     
     
       14. The pneumatic tire according to  claim 9 , wherein:
 the second inner lug groove extends from a location where an angle formed by a groove wall on a second outer circumferential main groove side of the inner circumferential main groove and the contact surface is smaller than an average value of a maximum value and a minimum value of an angle formed by a groove wall on a second outer circumferential main groove side of the inner circumferential main groove and the contact surface; and 
 the second outer lug groove extends from a location where an angle formed by a groove wall on an inner circumferential main groove side of the second outer circumferential main groove and the contact surface is smaller than an average value of a maximum value and a minimum value of an angle formed by a groove wall on an inner circumferential main groove side of the second outer circumferential main groove and the contact surface. 
 
     
     
       15. The pneumatic tire according to  claim 9 , wherein: a length of the first inner lug groove and a length of the first outer lug groove, or a length of the second inner lug groove and a length the second outer lug groove, are different from each other. 
     
     
       16. The pneumatic tire according to  claim 15 , wherein:
 the length of the first outer lug groove is longer than the length of the first inner lug groove. 
 
     
     
       17. The pneumatic tire according to  claim 15 , wherein:
 the length of the second outer lug groove is longer than the length of the second inner lug groove. 
 
     
     
       18. A pneumatic tire having a tread pattern and a predetermined mounting direction in a vehicle inner-outer side, the pneumatic tire comprising:
 an inner circumferential main groove having groove walls each extending in a tire circumferential direction while angles of the groove walls with respect to a contact surface vary with a predetermined amplitude; 
 an outer circumferential main groove located away from the inner circumferential main groove toward a vehicle outer side, the outer circumferential main groove having groove walls each extending in a tire circumferential direction while angles of the groove wall with respect to the contact surface vary with a predetermined amplitude; 
 an inner lug groove extending, from the inner circumferential main groove toward the outer circumferential main groove, partway along a region of a land portion between the inner circumferential main groove and the outer circumferential main groove; 
 an outer lug groove extending, from the outer circumferential main groove toward the inner circumferential main groove, partway along a region of the land portion between the inner circumferential main groove and the outer circumferential main groove; and 
 a sipe configured to communicate an end portion of an outer circumferential main groove side of the inner lug groove with an end portion of an inner circumferential main groove side of the outer lug groove, wherein 
 a width of the sipe expands toward a tread surface due to a pair of chamfered surfaces provided on walls of the sipe along an extension direction of the sipe on the contact surface; 
 wherein: 
 the inner lug groove extends from a location where an angle formed by a groove wall on the outer circumferential main groove side of the inner circumferential main groove and the contact surface is smaller than an average value of a maximum value and a minimum value of the angle formed by the groove wall on the outer circumferential main groove side of the inner circumferential main groove and the contact surface; and 
 the outer lug groove extends from a location where an angle formed by a groove wall on the inner circumferential main groove side of the outer circumferential main groove and the contact surface is smaller than an average value of a maximum value and a minimum value of the angle formed by the groove wall on the inner circumferential main groove side of the outer circumferential main groove and the contact surface. 
 
     
     
       19. A pneumatic tire having a tread pattern and a predetermined mounting direction in a vehicle inner-outer side, the pneumatic tire comprising:
 an inner circumferential main groove having groove walls each extending in a tire circumferential direction while angles of the groove walls with respect to a contact surface vary with a predetermined amplitude; 
 a first outer circumferential main groove located away from the inner circumferential main groove toward a vehicle inner side, the first outer circumferential main groove having groove walls each extending in a tire circumferential direction while angles of the groove walls with respect to the contact surface vary with a predetermined amplitude; 
 a first inner lug groove extending, from the inner circumferential main groove toward the first outer circumferential main groove, partway along a region of a land portion between the inner circumferential main groove and the first outer circumferential main groove; 
 a first outer lug groove extending, from the first outer circumferential main groove toward the inner circumferential main groove, partway along a region of the land portion between the inner circumferential main groove and the first outer circumferential main groove; 
 a first sipe configured to communicate an end portion of a first outer circumferential main groove side of the first inner lug groove with an end portion of an inner circumferential main groove side of the first outer lug groove; 
 a second outer circumferential main groove located away from the inner circumferential main groove toward a vehicle outer side, the second outer circumferential main groove having groove walls each extending in a tire circumferential direction while angles of the groove walls with respect to the contact surface vary with a predetermined amplitude; 
 a second inner lug groove extending, from the inner circumferential main groove toward the second outer circumferential main groove, partway along a region of a land portion between the inner circumferential main groove and the second outer circumferential main groove; 
 a second outer lug groove extending, from the second outer circumferential main groove toward the inner circumferential main groove, partway along a region of the land portion between the inner circumferential main groove and the second outer circumferential main groove; and 
 a second sipe configured to communicate an end portion of a second outer circumferential main groove side of the second inner lug groove with an end portion of an inner circumferential main groove side of the second outer lug groove; wherein: 
 a width of the first sipe expands toward a tread surface due to a pair of first chamfered surfaces provided on walls of the first sipe along an extension direction of the first sipe on the contact surface, 
 a width of the second sipe expands toward the tread surface due to a pair of second chamfered surfaces provided on walls of the second sipe along an extension direction of the second sipe on the contact surface, 
 the second inner lug groove extends from a location where an angle formed by a groove wall on the vehicle outer side of the inner circumferential main groove and the contact surface is smaller than an average value of a maximum value and a minimum value of the angle formed by the groove wall on the vehicle outer side of the inner circumferential main groove and the contact surface; and 
 the second outer lug groove extends from a location where an angle formed by a groove wall on the vehicle inner side of the second outer circumferential main groove and the contact surface is smaller than an average value of a maximum value and a minimum value of the angle formed by the groove wall on the vehicle inner side of the second outer circumferential main groove and the contact surface.